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Method for preparing sulfur dioxide and calcium oxide through anaerobic thermal decomposition of calcium sulfite

A calcium sulfite, sulfur dioxide technology, applied in the direction of calcium/strontium/barium oxide/hydroxide, chemical instruments and methods, inorganic chemistry, etc., can solve the problem of easy breakage, affecting the decomposition rate and thermal efficiency, and reducing the purity of the decomposition product lime and other problems, to achieve the effect of reducing product concentration, reducing processing cost, and promoting decomposition reaction

Active Publication Date: 2019-06-21
但建明
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Yet this invention has some deficiencies. First, in this invention, it is necessary to add extraneous substances to granulate the material, which will reduce the purity of the decomposition product lime and affect the reuse of lime; secondly, the granular material is easily damaged during the decomposition process. Reduce the utilization rate of calcium sulfite in desulfurization ash; finally, the efficiency of heat transfer performance between granular materials is low, which affects the decomposition rate and thermal efficiency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The embodiment of the present invention discloses a method for preparing sulfur dioxide and calcium oxide by using anaerobic thermal decomposition of calcium sulfite, which specifically includes the following steps:

[0036](1) Calcium sulfite pretreatment: press-filter the calcium sulfite slurry produced in the wet flue gas desulfurization process to ensure that its water content is 10% and the average particle size is 30 μm to obtain the calcium sulfite raw material;

[0037] (2) Aerobic drying preheating: the flue gas inlet of the first-stage cyclone drying preheater is the flue gas outlet of the third-stage spiral shaft preheating furnace, and the hot air obtained by anaerobic thermal decomposition is applied to the third-stage cyclone preheater. Heater cascade preheating, the calcium sulfite raw material pretreated in step (1) is spirally transported to the three-stage cyclone drying preheater for drying and heating, and then passes through the first-stage cyclone d...

Embodiment 2

[0041] The steps are the same as those in Example 1, the difference is that:

[0042] The calcium sulfite raw material obtained through pretreatment in step (1) has a moisture content of 20% and an average particle diameter of 60 μm;

[0043] In step (2), the air temperature at the inlet of each cyclone drying preheater is 425°C, 350°C, and 200°C respectively, and the temperature of calcium sulfite preheated by the first stage cyclone drying preheater is 380°C. ℃;

[0044] In step (3), the vacuum stabilization chamber maintains a slight negative pressure of 350Pa, and the temperature is maintained at 380°C;

[0045] In step (4), the temperatures in the third stage to the first stage spiral shaft preheating decomposition furnace are respectively: 600°C, 900°C, and 1000°C. A slight negative pressure of 500Pa is maintained in the furnace, and calcium sulfite is added to the spiral shaft at each stage. The residence time in the furnace was controlled at 20 minutes.

Embodiment 3

[0047] The steps are the same as those in Example 1, the difference is that:

[0048] The calcium sulfite raw material obtained through pretreatment in the step (1) has a moisture content of 5% and an average particle diameter of 100 μm;

[0049] In step (2), the air temperature at the inlet of each cyclone drying preheater is 500°C, 300°C, and 225°C respectively, and the temperature of calcium sulfite preheated by the first stage cyclone drying preheater is 390°C. ℃;

[0050] In step (3), the vacuum stabilization chamber maintains a slight negative pressure of 200Pa, and the temperature is maintained at 390°C;

[0051] In step (4), the temperatures in the third stage to the first stage spiral shaft preheating decomposition furnace are respectively: 700°C, 1000°C, and 1075°C. A slight negative pressure of 200Pa is maintained in the furnace, and calcium sulfite is placed on the spiral shaft of each stage The residence time in the furnace was controlled at 10 minutes.

[0052...

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Abstract

The invention discloses a method for preparing sulfur dioxide and calcium oxide through anaerobic thermal decomposition of calcium sulfite. High-purity calcium oxide and sulfur dioxide are obtained through indirect thermal decomposition of intermediate product calcium sulfite in wet desulfurization of flue gas under the anaerobic condition. Thermal decomposition of calcium sulfite comprises an aerobic drying preheating step, a vacuum deoxidation step and an anaerobic thermal decomposition step, wherein aerobic drying preheating can prevent calcium sulfite from being oxidized into calcium sulfate easily in the air at 450 DEG C or above, in the anaerobic thermal decomposition step, deoxidation of dried calcium sulfite in a micro negative pressure state is realized by use of an air lock valveat the lower part of a cyclone separator and a vacuum fan of a thermal-insulating flow stabilization bin. High-temperature anaerobic thermal decomposition of calcium sulfite is realized by use of a three-stage closed screw decomposition furnace, hot air obtained through anaerobic thermal decomposition performs stepped preheating on a three-stage heat preheater, and recycling of energy is realized. The method has excellent economic, environmental protection and social benefits and is suitable for promotion and application.

Description

technical field [0001] The invention relates to the technical field of preparation of inorganic products, in particular to a method for preparing sulfur dioxide and calcium oxide by anaerobic thermal decomposition of calcium sulfite. Background technique [0002] At present, the flue gas desulfurization method of coal-fired power plants mainly adopts limestone / lime-gypsum wet desulfurization. The method mainly includes two steps: one is the absorption process of sulfur dioxide, that is, sulfur dioxide in the flue gas reacts with limestone / lime to form insoluble calcium sulfite; A large amount of air is passed through to oxidize the calcium sulfite generated in step one into gypsum. Using this method to desulfurize the flue gas of coal-fired power plants requires a large amount of lime. Calculated on the basis of 1% sulfur content in coal, according to statistics, a 300,000-kilowatt power plant needs about 30,000 to 50,000 tons of calcium desulfurizer per year. , the nation...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B17/50C01F11/08
Inventor 但建明李洪玲王金玉
Owner 但建明
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